(1) Field of the Invention
This invention relates a substrate treating apparatus and a substrate transporting method therefor, that transport a plurality of substrates such as semiconductor wafers (hereinafter called simply substrates) with a transport device between a FOUP (Front Opening Unified Pod) capable of storing the substrates as sealed off from ambient atmosphere, and a treating section for cleaning and drying or otherwise treating the substrates.
(2) Description of the Related Art
Conventionally, this type of apparatus has an attaching and detaching mechanism for attaching and detaching a lid to/from an access opening of the FOUP (Front Opening Unified Pod), and mapping arms vertically movable, with the lid opened, in a stacking direction of the substrates to detect the number and positions of the substrates stored in the FOUP (see Patent National Publication No. 2002-527897, for example).
This substrate treating apparatus further includes a transport mechanism having a plurality of support arms and movable adjacent the access opening to transport a plurality of substrates from inside the FOUP (see Japanese Unexamined Patent Publication H11-354604, for example). After the lid of the FOUP is opened, the storage positions and number of substrates are determined by the mapping arms, and the transport mechanism in a transfer position extends the plurality of support arms into the FOUP to receive and take out a plurality of substrates all together.
The conventional apparatus with such a construction has the following drawback.
Although, in the conventional apparatus, the storage positions and number of substrates in the FOUP are determined by the mapping arms, the support arms of the trans-port mechanism having moved to the transfer position adjacent the access opening of the FOUP are not necessarily in positions fit for receiving the substrates.
In other words, since the FOUP has only a small space therein for storing the substrates, even if the transport mechanism is in the transport position, there is no knowing whether the support arms can transfer the substrates without interfering with the substrates. If the transport mechanism takes out the substrates in this state, the substrates can be damaged. It may seem that, where the transport mechanism is designed to have the support arms at a height not interfering with the substrates, the support arms will not interfere with the substrates as long as the transport mechanism has moved to the transfer position. In actual situations, however, there is a possibility of damaging the substrates due to bending of the support arms, a lowering in positioning accuracy at times of movement, or other causes.